The long term objectives of this grant are to understand the biochemical mechanisms by which sperm metabolism, motility and membrane function (capacitation and acrosome reaction) are regulated. Both the sea urchin and bovine systems will be used as models. Special emphasis will be placed on the potential involvement of cyclic nucleotides and of ion transport in the regulation of sperm function. In the sea urchin system, a small peptide (speract) which stimulates sperm metabolism and motility (but not the acrosome reaction) will be studied in detail. The receptor for speract will be identified, monoclonal antibody to the receptor will be produced and the location of the receptor on spermatozoa will be determined. The receptor will be purified and characterized and the speract-binding domain of the receptor will be isolated by HPLC after proteolysis; it will then be sequenced. Membrane vesicles which retain their ability to bind speract will be isolated and studied to determine whether or not speract activates a net H+ efflux from such vesicles, whether adenylate or guanylate cyclase can be activated and whether or not protein phosphorylation patterns are altered. Both Ser/Thr and Tyr phosphorylation will be studied. A factor(s) apparently secreted by bovine cumulus cells which stimulates bovine sperm forward motility will be partially characterized. Receptors for a large fucose-sulfate-rich polymer isolated from the jelly coat of sea urchin eggs, which induces the acrosome reaction and markedly elevates cyclic AMP, will be localized. Its effects on protein phosphorylation will be determined and adenylate cyclase will be used as a model enzyme by which to explain mechanism of Ca++ action. A factor(s) secreted by the cumulus oophorus cells which appears to inhibit the acrosome reaction in the bovine will be characterized. These will be the first studies to approach sperm-specific receptors in detail. Where specific receptors are located, how they function, and whether or not they can be manipulated to subsequently effect fertilization are important questions. Potential application of the work exists in the prevention of fertility, male sterility and in reproduction problems encountered in animals used as sources of food.